Solving Fluid Problem: Help with Planet X Orbit Period

  • Thread starter Thread starter shenwei1988
  • Start date Start date
  • Tags Tags
    Fluid
AI Thread Summary
The discussion revolves around calculating the orbital period of a satellite around Planet X, which is made of exoferrum with a density of 2810 kg/m3. Participants initially express confusion about the problem due to missing mass and radius values. Guidance is provided to use Newton's law of gravity and the volume formula for a sphere to derive the orbital period equation. By substituting the density into the gravitational formula, the correct relationship for the period is established. Ultimately, the participant successfully solves the problem with the provided hints.
shenwei1988
Messages
23
Reaction score
0
my professor gave us this problem on the homework assignment about Fluid.

Planet X is a sphere made entirely of the mythical metal exoferrum, which has density 2810 kg/m3. What is the period of orbit for a satellite in circular orbit just above the surface of Planet X? (That's right: I did not give you the mass or the radius of the planet!)


i have no ideal which equation i should use.

I don't know how to start this kind of problem ,please help!
 
Physics news on Phys.org
This has got nothing to do with fluids, and you have shown no work.

Could you have done it if r had been given?

Assume that some value has been given to you for the radius r, and just see how far you can proceed using 'r' as a symbol (or a number, if you like). If you get stuck, we are here.
 
using Newton's law of gravity, T^2= (4π^2*r^3)/GM

volume of sphere is V=4/3πr^3
ρ=M/V

put in Newton's law of gravity, T^2=3πV/GM T^2=3π/Gρ
 
thanks a lot, the hint you gave is so helpful. i got it right.
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Calculating Angle & Speed to Reach Planet's Moon from Station Orbit
Replies
1
Views
2K
From circular orbit to elliptical orbit
Replies
3
Views
2K
Find Density Given Period of Orbit
Replies
12
Views
5K
Planets and satellites, law of periods circular orbit.
Replies
15
Views
2K
Satellite Motion Homework: Find 2nd Satellite Speed
Replies
2
Views
2K
A satellite in orbit in a system with one planet and two moons
Replies
1
Views
1K
Finding the astronaut's weight on a planet's surface
Replies
9
Views
3K
Period of Planets orbiting a Star
Replies
13
Views
8K
Finding Orbital Period of Unknown Planet
Replies
5
Views
2K
How Does the Time Period Change with Orbit Radius in Satellite Motion?
Replies
10
Views
2K

Hot Threads

Recent Insights

Back
Top